Various types of continuous motion packaging machines are available for packaging articles such as bottles or cans into unitary containers such as paperboard cartons. While varied in detailed operation, such packaging machines function generally to gather articles into groups of a desired size and configuration and insert the grouped articles into the waiting cartons. A well known example of this type of packaging is found in six, twelve, and twenty-four pack cartons of canned soft drinks and beer. Other types of articles, such as bottled drinks and pet food, also are commonly packaged by such machines.
Continuous motion packaging machines can differ markedly in structure and detailed operation. In general, however, such machines function by moving articles and open cartons along adjacent synchronized longitudinal paths. As the articles are moved along, they encounter various guide rails and selector wedges that form the moving articles into moving groups aligned with the moving open cartons. Each group has a predetermined number of articles arrayed in a predetermined configuration. The moving groups of articles are then inserted into the waiting moving cartons. Insertion can be accomplished in a variety of ways, including shoving the grouped articles into cartons with transversely reciprocating paddles or herding the grouped articles gradually into their cartons with skewed guide rails. Once the article groups are inserted into their cartons, the cartons are sealed and conveyed away from the packaging machine.
Examples of continuous motion packaging machines can be found in U.S. Pat. No. 3,778,959 of Langen et al, 4,237,673 of Calvert., et al, 4,887,414 of Arena, and 5,241,806 of Ziegler et al. Ziegler et al discloses a machine wherein articles, once grouped, are shoved into waiting open cartons by reciprocating paddles. In Calvert et al, the grouped articles are herded into open cartons by skewed fixed guide rails. In some machines, such as that disclosed in Arena, grouped articles are moved onto a cardboard blank and the blank is subsequently folded and glued around the article group to form a carton for the articles.
A common requirement in continuous motion packaging machines wherein grouped articles are conveyed into preformed open cartons is that the cartons be stabilized and held down firmly as articles are inserted through their open ends. This is because the packaging machines tend to operate at high speed with many machines having the capability to package 2000 or more articles per minute. As a result, article groups tend to move into the open cartons with significant momentum that can displace or deform the carton if the carton is not stabilized and held firmly in place.
In the past, carton stabilizers on packaging machines typically have included a set of metal hold-down bars or rails mounted to the frame of the machine. These hold-down rails usually extend along and above the longitudinal path of the moving open cartons in the region where articles are inserted into the cartons. The rails are positioned to engage lightly and slidably the tops and, perhaps, the closed ends of the moving cartons as they are conveyed along the longitudinal path. As grouped articles are inserted into the open ends of the cartons, the rails stabilize and hold-down the cartons so that the substantial momentum of and force imparted by the articles does not displace or deform the cartons. In this regard, it has been found that careful spacing and positioning of the rails is critical to insure both adequate carton stabilization and high processing rates.
While such hold-down rail arrangements function adequately to stabilize the open cartons during article insertion, they nevertheless have been plagued with numerous problems and shortcomings inherent in their respective designs. One of the most crucial shortcomings has concerned the ease of adaptability of these hold-down devices to a change in carton size. Most continuous packaging machines can be configured to group and package articles such as beverage cans in a number of different configurations, such as, for example, six, twelve, and twenty-four article cartons. Obviously, when changing from one article configuration to another, the size of the carton required to accommodate the new grouping changes accordingly. Thus, the spacing and positions of the carton hold-down and stabilization rails must be changed to accommodate the new carton size.
Heretofore, such rail adjustment has required that the hold-down assembly be manually torn down and set up anew to accommodate the new carton size. Clearly, such a procedure consumes valuable processing time and requires the attention and resources of technical personnel. The problem is compounded by the critical relationship between carton size and shape and the spacing and positioning of the hold-down rails. If, for example, the rails bear too tightly against the cartons, the resulting friction can itself deform the cartons so that the articles will not move easily into the cartons. On the other hand, if the rails are too loose, the cartons can be deformed, displaced, or even destroyed by the momentum and force of the article groups as they are inserted into the cartons. Because of this critical relationship, it has not been uncommon that a number of wasteful test runs have been required after a reconfiguration to achieve the proper fine adjustment of the newly positioned hold-down rails. Adaptability problems such as these can become particularly acute and costly where article configuration and carton size is changed frequently.
Thus, it is seen that there exists a continuing and as yet unaddressed need for a carton hold-down and stabilization method and apparatus for packaging machines that effectively stabilizes and holds down open moving cartons as articles are inserted into the cartons, that can be adapted quickly, easily, and without the resources of technical personnel to virtually any new article configuration and cartons size, and that, once adapted, performs its function properly with the new carton size without wasteful test runs to accommodate fine adjustment. It is to the provision of such a stabilization and hold-down method and apparatus that the present invention is primarily directed.